Mixer-refiner

ABSTRACT

A high viscosity material mixer-refiner having a cylindrical stator shell and rotor has improved refining surfaces on the rotor and stator. These are formed of interchangeable blocks held in place on the rotor and the stator with the blocks having teeth oriented in different aspects to the relative motion between the rotor and the stator. The teeth are preferably raised bars with orientations for advancing or retarding material. The blocks are arranged in desired patterns to accomplish optimum mixing and refining.

United States Patent [191 Cumpston, Jr.

[451 Apr. 23, 1974 MIXER-REFINER [76] Inventor: Edward H. Cumpston, Jr.,43

Monument Ave., Bennington, Vt. 05201 [22] Filed: May 9, 1972 [21] Appl.No.: 251,779

Related US. Application Data [63] Continuation-impart of Ser. No.142,501, May 12,

1971, abandoned.

2,978,192 4/1961 Cumpston 241/260 X 3,221,999 12/1965 Cumpston.....241/260 X 3,323,733 6/1967 Brown 241/260 X 3,326,480 6/1967 Jones241/300 X Primary Examiner-Granville Y. Custer, Jr. AssistantExaminer-Howard N. Goldberg Attorney, Agent, or Firm-Cumpston, Shaw &Stephens [57] ABSTRACT A high viscosity material mixer-refiner having acylindrical stator shell and'rotor has improved refining surfaces on therotor and stator. These are formed of interchangeable blocks held inplace on the rotor and the stator with the blocks having teeth orientedin different aspects to the relative motion between the rotor [56]References Ci d and the stator. The teeth are preferably raised barsUNITED STATES PATENTS with orientations for advancing or retardingmaterial. I 593 153 7/1926 A bl H298 X The blocks are arranged indesired patterns to accomy m er 2,968,444 l/l961 Jones 241/260 x phshpnmum f andlefinlng 2,970,783 2/1961 Cheyette 241/300 32 Claims, 27Drawing Figures I d 20 I0 II 24 1a 5a l| '7/\ Q- w r ROTATION OUTLETHOLD 24a 27 FIG. 3

OUTLET E o I u l g 2: Lu 27 2 2 l 28 23a FEED FIG. 6

MA TERIAL FLOW mil 2 UP 9 ROTATION OUTLET OUTLET I28 FIG. 10

24c NEUTRAL 27 FIG- 5 OUTLET.

s 5 2 W E 23 NEUTRAL FIG. 8

INVENTORJ EDWARD H. CUMPSTON JR.

BY W 2 ATTORNEYS PATEMTEDAPR 23 mm 3,806050 m s or 9 FIG. l6

PATENTED APR 2 3 I974 01w 7 [IF 9 HO!) xx STATOR HOLD STATO R FEED FIG.I?

FKS. l9

IIOa

FIG 20 PATEHTEU APR 2 3 19m SHEET 8 [BF 9 Mn g UTLET I Hlb ROTOR HOLDP16. 22

I "'3 L a K ROTOR FEED MIXER-REFINER RELATED APPLICATIONS Thisapplication is a continuation-in-part of my parent application, Ser. No.142,501, filed May 12, 1971, entitled Improved Refiner, and abandonedupon the filling of this application.

BACKGROUND OF THE INVENTION Highly viscous materials bordering betweensolids and fluids present special problems in mixing, refining Theinvention involves recognition of the importance of controlling the flowof highly viscous material for mixing or refining, and devising of asimple and efficient way of controlling and varying the flow of suchmaterial as it passes through a refiner. The invention includes improvedrefining surfaces for a generally known cylindrical mixer-refiner havingan internal rotor and a stator shell, and the improved refining surfacesare developed for optimum control of the move ment and mixing of thematerial as it passes through the refiner to avoid packing, solid-liquidseparation, and to ensure optimum and even mixing and refining.

SUMMARY OF THE INVENTION The invention provides improved refiningsurfaces for a high-viscosity material mixer-refiner having an internalrotor and a stator shell forming a cylindrical refining region. Therefining surfaces are formed for a plurality of stator and rotor blockshaving teeth and removably and interchangeably held in placerespectively on the stator and rotor. The teeth are preferably raisedbars with inclined leading edges, and the set of blocks for both therotor and the stator includes blocks having teeth oriented in differentaspects to the relative motion between the rotor'and stator, preferablyfor advancing material and retarding material. By arranging the blocksas desired, preferably in grooves spaced around the stator and rotor,regions for feeding and holding can be established as desired along thelength of the refiner and around its circumference to process thematerial as desired. Hundreds of patterns can be used to adapt a refinerfor optimum processing of any viscous material since the severity of theprocessing treatment of a material flowing through the refiner isdependent on how much of the material is layered between the shell androtor surfaces, and this material build-up is controlled by the flowpattern arrangement of the blocks mounted on the rotor and stator.

THE INVENTIVE IMPROVEMENT Both dry solid materials and relatively lowviscosity fluid materials are fairly easy to mix and process inconventional equipment, but the poor flowability of highly viscousmaterials produces uneven and unreliable processing even where suchmaterials can be passed through conventionalequipment. A materialpresenting such problems is high-viscosity paper-pulp materialcontaining cellulose fibers and relatively little moisture. In a lessviscous state, such material is quite flowable and readily controlled,but cannot be refined readily because the liquid protects the fibers. Ina highly viscous state, such material can be refined to produce strongerpapers and other advantages, except that controlling the flow anduniform mixing and refinement of the material has been unsatisfactory.The shear forces that occur when such high viscosity material is forcedbetween refining surfaces is sufficient to accomplish the desiredrefining if the mixing is thorough and even, if the flow is accuratelycontrolled, and if the material is kept from packing up or speedingthrough the refiner.

Causing the material to flow through a disk refiner is relatively easy.For example, almost any material can be made to flow through a disk millbecause of the high centrifugal forces and the open discharge.Controlling the flow in a disk mill is extremely difficult, however,because any method of retaining material by resisting the centrifugalforces is subject to immediate plugging by these highly viscous andnon-flowing materials. This is particularly true of thick, fibroussuspensions which, under pressure, can thicken into a solid mass.

The inventive mixer-refiner avoids the problem of trying to restraincentrifugal force by forming a cylindrical refining region with materialmoving parallel to the axis of the machine. Processing occurs betweenthe working surfaces of an internal rotor and a stator shell defining acylindrical refining region. The confronting surfaces of the rotor andstator have working teeth that both mix and refine the material andcontrol its flow through the machine, and these teeth are oninterchangeable blocks preferably mounted in longitudinal, dovetailedgrooves. The circumferential surfaces between the grooves is generallycylindrical and flush with the bottom of the exposed teeth which arepreferably formed as raised working bars with inclined leading edges.The result is a rotating inner surface and a stationary outer surfacewhich are generally smooth and cylindrical except for the raised barsprovided by the blocks. These bars are spaced apart between adjacent,axial blocks, and radially spaced across the grooves to afford smoothregions for turbulent flow of material between sets of working bars. Theblocks can be interchanged longitudinally in a groove orcircumferentially from one groove to another to accomplish manydifferent patterns.

Each block is independent of all other blocks, and the sets of blocksfor both the rotor and stator preferably include teeth oriented indifferent aspects to the relative motion between the rotor and thestator. These orientation aspects preferably include bars angled to feedor advance material toward the outlet and bars angled to retard or movematerial toward the inlet to hold material between the stator and rotorsurfaces to produce a more densely packed layer resulting in increasedrefining action on the material. Also, neutral bars that neither advancenor retard material but mix, shear, and refine the material as they moverelative to the material can be added.

With these three teeth orientations of blocks, and with blockinterchangeability, flow of a material can be promoted and controlled tosuit the material being processed. For example, if a material tends topack too tightly between the refining surfaces to consume too much powerand cause excessive refining, then rearranging the blocks orsubstituting additional feed or advancing blocks will increase the flow,reduce the retention of material, and cause the desired refining action.In general, if more feed blocks are used on the stator surface and morehold blocks on the rotor surface, the refiner will tend to be selfstabilizing over a fairly'wide range of operating conditions. It hasbeen found, however, that when changing from one kind of material toanother an entirely different arrangement of blocks may be required.Also, flow control in the inventive mixer-refiner is described morefully below.

These are two basic approaches to arranging feed and hold blocks toachieve the desired flow pattern. Feed and hold blocks may be alternatedby longitudinal rows, or may be alternated in circular rings, and thesetwo approaches can be intermixed in many ways. The inter-action betweenthe shell and rotor hold and feed blocks adds even more flexibility.This is discussed more fully below.

It is preferred for successful operation of the mixerrefiner thatmaterial being processed be kept -constantly moving to prevent packingwhich might interfere with throughput flow. To ensure this constantmotion and mixing action, the refining blocks are designed to produceconstant circumferential circulation of material. The raised workingbars are never angled so steeply from the path of relative motion thatthe slippage through the material is prevented. The leading edges of thebars are inclined, and the bars are spaced apart and their sides slantedso they will not pack material. The bars are smooth surfaced, andgenerally smooth cylindrical surfaces are provided between axial rows ofblocks on both the shell and rotor surfaces to allow material to slideand mix between each row of blocks. Material is tumbled, sheared, andmechanically thrown either toward the machine outlet or inlet toaccomplish mixing and refining without creating fluid pressure whichtends to separate solids from liquids.

DRAWINGS FIG- 1 is a partially schematic, axial cross section view of apreferred embodiment of the inventive machine; I

FIG. 2 is an enlarged, fragmentary cross section of the machine of FIG.1 taken along the line 2 2 thereof;

FIG. 2A is an enlarged, fragmentary cross section of a rotor block fromFIG. 2;

FIGS. 3 8 are plan views of preferred embodiments of stator and rotorblocks;

FIGS. 9 and 10 are enlarged, fragmentary, crosssectional views of theblocks of FIGS. 4 and 7 respectively as indicated;

FIGS. 11 and 12 are schematic, plan views of one of many preferred blockarrangements for a rotor and shell laid out flat;

FIG. 13 is a longitudinal, cross-sectional view of an alternative,preferred embodiment of the inventive mixer-refiner;

FIG. 14 is a fragmentary transverse, cross-sectional view of themixer-refiner of FIG. 13, taken along the line 14 14 thereof;

FIG. 15 is a longitudinal, cross-sectional view of another preferredembodiment of the inventive mixerrefiner;

FIG. 16 is a fragmentary, transverse, cross-sectional view ofthemixer-refiner of FIG. 15, taken along the line 16 16 thereof;

FIGS. 17 and 18 are plan views ofstator blocks preferred for themixer-refiner of FIG. 15;

FIG. 19 is an enlarged, fragmentary, cross-sectional view of the workingbars of the stator block of FIG. 17 taken along the line 19 19 thereof;

FIG. 20 is an end elevational view of the stator blocks of FIGS. 17 and18;

FIGS. 21 and 22 are plan views of rotor blocks preferred for themixer-refiner of FIG. 15;

FIG. 23 is an enlarged fragmentary, cross-sectional view of the workingbars of the rotor block of FIG. 21 taken along the line 23 23 thereof;

FIG. 24 is an end elevation of the rotor blocksof FIGS. 21 and 22; and

FIGS. 25 and 26 are fragmentary, cross-sectional views of the stator barclamping arrangement, taken respectively along the lines 25 25 and 26 26of FIG. 16.

DETAILED DESCRIPTION Refiner 9 also includes a base 13, a hopper inlet14, .an open gravity discharge chute 15, a combination lump breaker andfeed screw 16for forcing material from hopper 14 into the refiner and adisk mill type material feeder 17 having rotating bars 18 that confrontstationary bars 19 across a narrow gap. The disk feeder 17' takesmaterial away from screw 16, ensures that it is broken down to a sizesuitable for refining, and by centrifugal force drives the material intorefiner 9. A cylindrical refining region 20 is formed between statorshell- 21 and rotor 22 mounted on shaft 10 for rotation inside shell 21.Refining region 20 extends axially for the length of shell 21 and [rotor22 to refine the materials fed from disk mill 17 and discharge therefined material through chute 15. The improvement in refiner 9 involvesthe formation of the refining surfaces along region 20. The detailsofthis are shown more fully in FIGS. 2 12. I

As best shown in FIG. 2, grooves 31 extend axially the length of shell21, and grooves 32 extend axially the length of rotor 22. The edge ofgroove 31 that trails relative to material motion is formed as adovetail 33, and the edge of groove 32 that trails relative to rotationof rotor 22 has a dovetail 34. Stator blocks 23 are bedded in grooves 31with their trailing edges resting in dovetail 33, and rotor blocks 24are bedded in grooves 32 with their trailing edges resting indovetail'34. Stator blocks 23 and rotor blocks 24 preferably have thesame axial dimension, although stator blocks 23 have a somewhat greatercircumferential dimension. Grooves 31 and 32 are filled with respectiveblocks 23 and 24 with such blocks in axial abutment. To avoid having anunswept circular path of material, the refiner 9 is made a whole numberof blocks long plus about 1 inch extra for blank spacers 25 shaped tofit in grooves 31 and 32. By alternating spacers 25, the junctionsbetween adjacent blocks in rows of blocks on stator 21 and rotor 22 arestaggered to offset the refining blocks and eliminate any unswept area.This is also shown in FIGS. 11 and 12.

Blocks 23 and spacers 25 are secured in place by dovetail shaped clampbars 35 that are drawn into groove 31 by screws 36 through stator 21.Similar dovetailed clamp bars 37 are drawn into grooves 32 by screws 38to hold blocks 24 and spacers 25 in place in rotor 22. Any desiredarrangement of blocks 23 and 24 can be made by removing clamp bars 35 or37 and arranging interchangeable blocks as desired. Each of the blocks23 and 24 is preferably cast of a hard metallic alloy and has itsdovetailed shape base cast or potted in an epoxy or other plastic grout26 as shown in FIG. 2A to produce the precise shape to fit dove-tailedslots 31 and 32.

Blocks 23 and 24 clear each other by about onequarter inch when theblocks are new, and they are preferably replaced when their clearancewears to about five-eighths inches. The refiner shown in the drawing isa pilot-sized machine having six axial grooves 31 and 32 in stator 21and rotor 22 for holding six rows of blocks with each row being sixblocks long for a total of 36 blocks in the refining surfaces of stator21 and rotor 22. The inside surface of stator 21 is preferably smoothand flush with the base portion of blocks 23, and the outer surface ofrotor 22 is also generally smooth and flush with the base portion ofblocks. 24. The spaces between rows of blocks 23 and 24 allow materialto collect and move to flow smoothly from one working surface to thenext without-plugging or packing. Also, the working surfaces of each ofthe blocks 23 and 24 leave some space along the axial edges of suchblocks to prevent plugging or packing.

The working surfaces of blocks 23 and 24 preferably comprise teethformed as bars 27 raised above the base portion of the blocks asschematically illustrated in FIG. Bars 27 are generally smooth withsloping sides and extend about one-half inch beyond the base of theblocks to clear each other by about one-quarter inch. The leading ends28 of working bars 27 are beveled back at about 60 to a radial line toprevent hang-up of material on leading edges 28. Blocks 23 and 24 aresecurely supported by dovetails 33 and 34 at their trailing ends, andclamp bars 35 and 37 secure leading ends tightly into grooves 31 and 32.Preferred details for the working surfaces for blocks 23 and 24 arebetter shown in FIGS. 3 which illustrate block castings lacking theplastic grout 26 shown in FIG. 2A.

Three preferred forms of rotor blocks 24 are shown in FIGS. 3 5 and 9.Block 24b of FIG. 4 has its teeth 27 inclined by preferably about fromthe rotation direction of the rotor for feeding material toward theoutlet of the refiner as indicated by the arrow. The preferredcross-sectional shape of working bars 27 is shown in FIG. 9, and thesame shape is used for tooth bars 27 on block 24a of FIG. 3 where bars27 are inclined by about 15 from the direction of rotation to hold backorretard material and force it back toward the inlet of the machine. Aneutral, refining block 24c is shown in FIG. 5 with its working teeth 27following the direction of rotation so as not to feed or retardmaterial. Teeth 27 of block 240 pass through, shear, and mix thematerial being refined, and tend to carry such materialcircumferentially, but neither advance nor retard it.

Three preferred orientations of stator blocks 23 are shown in FIGS. 6 8and 10. Block 23b of FIG. 7 has its teeth 27 inclined as illustrated sothat material tending to move in the direction of the arrow is directedaway from the outlet of the machine and toward the inlet for holdingback or retarding the material. Teeth 27 on block 23 are preferablyangled about 10 from the direction of material motion, and are spacedfurther apart than the bars 27 on rotor blocks 24. This is to ensurethat material slips or moves along in the stator in spite of the effectof centrifugal force which tends to pack the stator and keep the rotorclear. The smaller inclination and wider spacing of teeth 27 on block2312 prevents plugging or packing of material into the stator.

Teeth 27 of block 23a of FIG. 6 are the same as the teeth on block 23bexcept they are angled by approximately 10 from the material flowdirection to feed material along toward the outlet of the refiner. Teeth27 on neutral block 230 follow the line of material motion, and refinematerial without feeding or holding back.

FIGS. 11 and 12 schematically show one of many preferred arrangementsfor rotor blocks 24111, b, and c, and stator blocks 23a, b, and 0. Eachof these blocks is marked F for feeding H for holding back, and N forneutral refining, and the blocks are shown as laid flat. Generally, theflow control blocks for feeding and holding back are preferably spacedboth longitudinally and circumferentially. The arrows representalternating feed and hold rings which oppose each other tending to trapmaterial between them and thus ensure a full layer of material in thecylindrical refining zone. The use of blank spacers 25 is shown forstaggering rowsof blocks.

Since the original application was filed an experimental model of theinventive mixer-refiner was built and tested. This led to someimprovements in the invention and to a better understanding of itsoperation. From this work, two preferred embodiments of the inventivemixer-refiner have emerged, and these are described below, along withsome of the improvements. Also, the operation of the equipment isexplained more fully.

A relatively small mixer-refiner 40 is shown in FIGS. 13 and 14. Itincludes a fixed cylindrical stator 41 supported on a base 42 and acoaxial, internal rotor 43 supported on shaft 44. Bearings 45 and 46support shaft 44 for being driven by a motor (not shown) .for turningrotor 43 inside of stator 41.

Material for mixing and refining is input to machine 40 through chute 47where it is fed axially of sleeve 48 by screw 49. A disk refiner 50 atthe input region of machine 40 has stator bars 51 and confronting rotorbars 52 for breaking up the input material into relatively small bitsfor mixing and refining in machine 40. The mixed and refined materialpasses through an outlet opening 53 and is discharged out of chute 54.

Stator 41 and rotor 43 respectively carry interchangeable blocks 55 and56 having respective raised bars 57 and 58 for mixing and refiningmaterial along the length of machine 40. Stator blocks 55 are similar toblocks 23A and B of FIGS. 6 and 7 and rotor blocks 56 are similar toblocks 24A and B of FIGS. 3 and 4. Blocks 55 and 56 are preferably castof a relatively hard metal and preferably have their bases potted inepoxy to form epoxy coatings 59 and 60. Preferably the epoxy coating isformed in a single mold for all stator blocks 55, and is another moldfor all rotor blocks 56, so that epoxy coatings 59 and 60 are accuratelyuniform for all blocks 55 and 56. Then blocks 55 and 56 can beaccurately mounted in place with improved clamping bars as best shown inFIG. 4 and described below. I

Stator 41 is preferably formed of a pair of semi cylindrical shells 61having flanges 62 that are bolted together. Several radial annuli 63surround and strengthen shells 61, and axial bars 64 extendlongitudinally of shells 61 and pass through radial annuli 63. Theresult is a sturdy and rugged stator 41.

Stator blocks 55 are held in place on the inside of shells 61 by clampbars as described below. Axial slots 65 are formed through shells 61 andradial plates 63 to extend the length of stator 41. A clamp bar 66 and awedge bar 67 extend through each of the slots 65 and are respectivelyheld-in place by screw levers 68 and 69. Clamp bars 66 and wedge bars 67have dovetail shaped heads inside shells 62 and flat bodies that extendthrough slots 65 and are notched along their length tofit into notchedrelationship with annular plates 63;

Bars 66 and 67 are held against radial movement by screw levers 68 and69 that extend through bars 66 and 67 and through holes 70 in axial bars64. Each of the screw levers 68 and 69 has a fulcrum pin 71 restingagainst shell 61 and a screw 72 turned against shell 61 to draw screwlever 68 or 69 away from the shell 6l.

Screw levers 68 pass through and engage holes 73 in clamp bars 66 todraw bars 66 tightly against the leading ends 74 of stator blocks 55when screws 72 are 66 but holes 77 are large enough so that screw levers69 do not engage clamp bar 66.

When drawn tight in slots 65, wedge bars 67 provide a fixed, abutmentsurface sturdily supporting the trailclamped firmly in place in shells61 with the heads of bars 66 and 67 forming generally smooth surfacesbetween each row of blocks 55.

The rows of blocks are preferably staggered or offset relative to eachother by means of spacers 79 positioned at alternately opposite ends ofsuccessive rows of blocks 55. Since all the blocks 55 have pottedcoatings 59 that are preferably formed in the same mold, coverings 59form uniform bases so that all the blocks 55 can be accurately clampedin place by bars 66 and 67. I

Rotor blocks 56 are also clamped in place in rotor 43. Axial grooves 80are formed in rotor 43 to receive rows of blocks 56, and grooves 80 havea wedge-shape 81 for receiving and supporting trailing edges 82 ofblocks 56. This gives a fixed and firm' support to each row of blocks56. At the leading edge 83 of blocks 56 an axial wedge bar 84 is wedgedin place by screws 85 to clamp leading edges 83 snugly in place for eachrow of blocks 56. Wedge bars 84 are preferably wedgeshaped asillustrated for a tight, wedged fit augmenting the holding power ofscrews 85.

Relatively smooth and open surfaces 86 adjacent wedge bars 84 separaterows of blocks 56. Rows of blocks 56 are also preferably staggered oroffset relative to each other by spacer blocks 87 arranged at alternateends of each row of rotor blocks 56.

The improved clamping of blocks 55 and 56 in place in machine 40simplified the machine and reduces the construction costs, and alsoimproves on the security and convenience of the clamping so that blocks55 and 56 can be readily replaced, interchanged, or moved. The epoxycoatings 59 and 60 give the blocks uniform and durable basesfacilitating such a clamping arrangement. The operation of machine 40will be described below.

Machine 90 is another preferred embodiment of the inventivemixer-refiner and is made larger than machine 40 and capable of greaterpower and mixing rate. It includes a cylindrical stator 91 supported ona base 92 and containing a cylindrical rotor 93 mounted on shaft 94turned by a motor (not shown). Material is input through a chute 95 to arotating sleeve 96 carrying a screw 97 for feeding material axially intodisk re-. finer 98. Output is through an opening 99 in end plate 100,and through a discharge chute 101.

Stator 91 is formed of a pair of semi-cylindrical shells 102 havingflanges 103 bolted together. Radial plates 104 extend around the outsideof shells 102,'and axial bars 105 extend through radial plates 104 forthe length of stator 91. Rotor 92 is'formed of radial plates 106 securedto shaft 94and carrying axial bars 107.

Stator 91 has interchangeable blocks 110 arranged in axial rows insideshells 102, and rotor 93 has interchangeable blocks 111 arranged inaxial rows on plates 107. Blocks 110 and 111 are preferably epoxy-pottedto have respectivecoatings 112 and 113 as previously described and asshown in FIG. 16. Stator spacer blocks 114 are placed alternately atopposite ends of rows of stator blocks 110 to stagger or offset therows, and rotor spacer blocks 115 are similarly used to offset rows ofrotor blocks 111. Stator and rotor blocks 110 and 111 are shown ingreater detail in FIGS. 17 24 and are described more fully below. Themounting of blocks 110 and 111 is best shown in FIG. 16.

Stator blocks 110 are preferably clamped to the inside of shells 102 ina similar manner to that described above for machine 40. Axial slots 116 are formed along the length of shells 102 and extend into radialplates 104 to receive and support wedge bars 117 and clamp bars 118 thatextend axially the length of stator 91. Wedge bars 117 have notches 119along their length to seat against plates 104, and clamp bars 118 havedeeper notches 120.along their length to clear plates 104. This allowsclamp bars 118 to move radially in slots 116, and allows wedge bars 117to seat firmly in a radially outermost position resting against plates104.

The heads of bars 117 and 118 are dovetailed as illustrated so thatwedge bar 117 provides a fixed, angled recess receiving the trailingedges of a row of stator blocks ll0,'and clamp bar 118 is drawn tightagainst the leading edges of a row of stator blocks 110. The heads ofbars 117 and 118 provide a generally smooth and open space between rowsof stator blocks 110.

Bars 117 and 118 are held in place by screw levers 121 and 122 extendingthrough holes in bars 117 and 118 and through holes 123 in axial bars105. Each of the screw levers 121 and 122 has a fulcrum end 124 restingagainst the outside of shell 102, and can be levered away from shell 102by a screw 125.

As best shown in FIG. 25, wedge bar 117 has a hole 126 that is enlargedat one end for loosely receiving screw lever 122 and narrowed at theother end for engaging screw lever 121. Then as the screw 125 in screwlever 121 is tightened, screw lever 121 is driven against the narrowedge of hole 126 to force the notch 119 of wedge bar 117 into firmengagement with plate 104. At the same time, screw lever 122 has somefreedom movement in the other end of hole 126.

As best shown in FIG. 26, clamp bar 118 has a hole 127 that is enlargedat one end for loosely receiving screw lever 121 and is smaller at theother end for engaging screw lever 122. Then as screw 125 in screw lever122 is turned against shell 102, screw lever 122 engages the narrow endof hole 127 and moves clamp bar 118 radially outward for drawing thehead of bar 118 snugly against the leading edges of a row of statorblocks 110. The general result is the same as previously described, inthat several rows of stator blocks 110 are firmly and convenientlysecured in place inside shells 102 and are replaceable ofinterchangeable simply by loosening and removing bars 117 and 118.

Rotor blocks 111 are secured in place in axial rows on rotor.93 bymeansof wedge bars 129'and clamp bars 130. Wedge bars 129 extend axially ofrotor 93 in a radial slot and have a projection 131 lodged in a notch132 to fix wedge bars 129 radially in place. Then the dovetailed-shapedhead of wedge bar 129 provides a fixed and rigid support for thetrailing ends of a row of rotor blocks 111.

Clamp bars 130 also extend axially of rotor 93 and are adjacent wedgebars 129 in a radial slot in rotor 93. Clamp bars 130 have smallerprojections 133 that are free to travel radially in notches 134. Anotheraxial bar 135 is trapped in a notch 136 so that bar 135 cannot moveradially outward from notch 136. Bar 135 has an axial succession ofthreaded holes for receiving bolts 137 extending through clamp bars 130and screwed into bars 135 for drawing clamp bars 130 radially inward todraw their dovetailed heads tightly down against the leading edges of arow of rotor blocks 111. The heads of bars 129 and 130 provide agenerally smooth and open area between rows of rotor blocks 111, andbars 129 and 130 provide a secure and convenient clamping arrangementfor holding rotor blocks lllfirmly in place around rotor 93.

The preferred details for stator blocks 110 for machine 90 are bestshown in FIGS. 17 20. Stator block 110a of FIG. 17 has two rows ofraised bars 138 oriented to feed material toward the outlet of themachine. Each of the bars 138 is generally trapezoidal with a flat topand tapered sides as best shown in FIG. 19, and the leading edges 139 ofbars 138 are preferably angled back from the machine radius by about 60.Also, bars 138 are preferably angled about from the direction ofrelative motion between rotor 93 and stator 91.

The two rows of bars 38 on block 110a are offset so that the spacesbetween bars 138 are not aligned. This requires material passing throughthe foremost row of bars 138 to turn toward one side or the other topass It is also possible to use neutral stator blocks having barsaligned with the relative motion between stator 91 and rotor 93, andsuch neutral blocks were described previously relative to FIG. 8.Experience with the inventive machine has shown that at least forcellulose fiber material, combinations of feed blocks A and hold blocks1108 are preferred to neutral blocks.

The preferred rotor blocks for machine 90 are best shownin FIG. 21 24,without the molded epoxy covering 113 that is preferably applied beforethe blocks are assembled into machine 90. Rotor block 111A of FIG. 21has two rows of raised bars 140 oriented to feed material toward theoutlet of machine 90. Bars 140 are-preferably angled about 15 from thedirection of relative motion between rotor 93 and stator 91, and their.leading edges 141 are preferably angled back from the machine radiusbyabout 60. As best shown in FIG. 23, bars 140 are generally trapezoidalin shape with sloping sides, but the tops 142 of bars 140 are preferablysloped downward toward the leading or working edges 143 of bars 140 asillustrated. Because of the angle of bars 140, edges 143 are leading orobliquely working their way into the material in the machine, and tops142 are sloped downward toward top edges 143. This gives bar tops 142 anoutward cam ming action against the material which is engaged obliquelyby edge 143 and moved radially outward as the material tends to slideover bar tops 142.

Rotor block 1118 of FIG. 22 is the same as block 111A except that theraised bars 143 on block 1118 have the opposite angular orientation forholding back material or moving material away from the machine outlet.Rotor neutral blocks such as shown in FIG. 5 can also be used in machine90, but for most materials,

combinations of feed blocks 111A and hold blocks 11 1B are preferred.

OPERATION Experience with the invention since the parent patentapplication was filed has made its operation more clear and has shownthat the invention has more uses than originally anticipated. Forexample, the inventive machine is an excellent mixer as well as arefiner, and can be used for mixing many highly viscous materials. Themachine was originally built for refining thick suspensions of cellulosefibers, but many other highly viscous materials can be mixed, refined,or thoroughly contacted with a gas.

An example of material that can be mixed in the highly viscous stage inthe inventive machine, but not in other equipment is ink which is amixture of solid materials in a solvent. The only previously known wayof mixing the solid ink materials in with the solvent was to mix at afairly low viscosity. This then requires shipping considerable solventweight along with the ink solids. In the inventive machine, ink solidscan be mixed with a solvent at a high viscosity thoroughly enough sothat the ink can be shipped in a highly concentrated form and dilutedwith more solvent at the printing site. This effects substantialeconomies.

Another accomplishment of the inventive mixerrefiner is to break downand mix impurities and spread them so thoroughly throughout cellulosefibers that they do not cause any problem in paper-making machines. Forexample, glue, asphalt, and plastic materials find their way into wastepaper for recycling, and even small bits of these materials'can stick toa papermaking machine and require shutdowns and clean-up. However, theinventive mixer-refiner breaks down adhesives and other troublesomematerials into minute particles and mixes them so thoroughly withcellulose fibers that in effect they disappear and do not cause anyproblems.

It has been discovered in operating the inventive machine that properarrangement of stator and rotor blocks accomplishes automatic mixingcontrol. To

achieve this, the stator is formed of a combination of i overall.neutral feed orientation, or with hold blocks.

slightly predominating so that the rotor tends to hold rather. thanfeed.

Then as material is introduced to the machine, the rotor throws itcentrifugally outward into the stator bars, and the stator barsgradually fill with material without much mixing or refining. Whenmaterial builds up in the stator sufficiently to bridge the gap betweenthe stator and rotor bars, it is worked on by the rotor bars as well.Rotor bars are formed to have a better frictional grip on the materialso that before the rotor bars fill with material, they grip the materialfirmly enough to begin spinning it through the stator bars. The materialis tumbled, turned, moved around corners, and over edges of the statorbars, and is engaged and pressed by edges of the rotor bars andsubjected to considerable turbulence in the generally clear areasbetween bars. Since the stator bars are generally oriented to feed, thematerial begins to move toward the outlet as the rotor bars spin thematerial through the stator bars. Since the bars are discontinuous orseparated by open space, there is no single, comfortable path from theinlet toward the outlet, and the material is constantly tumbled, pushedforward and backward, and moved'over edges of the working bars as itproceeds along toward the outlet.

if the material input rate slows down for some reason, feeding alsoslows down because feeding occurs only when there is sufficient materialbetween the rotor and the stator for the rotor to grip the material andspin it through the stator bars. This ensures that no material passesthrough the machine without being thoroughly mixed, because feedingoccurs only at times of substantial mixing.

It is important that the rotor bars have a better frictional grip on thematerial than the stator bars to achieve the desired relationshipbetween mixing and feeding. The better grip of the rotor bars can beachieved in several ways, and the preferred arrangement is to inclinethe rotor bars at a greater angle than the stator bars relative to themotion between the rotor and the stator. Hence, in the illustratedembodiments,

the rotor bars are preferably angled 15 from the radial plane, and thestator bars angled only 10 from the radial plane. Other possibilitiesare to make the rotor bars more numerous and closer together, to. givethe rotor bars a greater total length of working edges, or to make therotor bars taller than the stator bars. The general and desired effectof any of these arrangements is that the rotor grips the material moreforcefully than the stator so that the rotor generally drives thematerial which slides through thestator bars in-response to the rotorforce and is fed through the machine only when driven by the rotorthrough the stator bars.

Several variations in hold and feed patterns can be used. For example,rotor and stator blocks can be arranged for predominantly feedingmaterial near the input region of the machine,-and for predominantlyholding back in zones away from the input. One preferred region forholding back material is near the outlet of the machine, and otherholding back regions can be spaced along the axis of the machine. Forsome materials it may be desirable to give the rotor a heavypredominance of hold blocks, and other materials are better mixed with arotor that has equal numbers of hold and feed blocks. Also, thepredominance of the feed orientation of the stator can be modified withdifferent materials. Blocks on both the rotor and stator are preferablyalternated or mixed to avoid any solid ring of either feed or holdblocks. The open spaces between the bars on stator and rotor blocks arealso important to allow space for turbulence of the material leaving onegroup of bars and entering another group of bars.

Persons wishing to practice the invention should remember that otherembodiments and variations can be adapted to particular circumstances.Even though one point of view is necessarily chosen in describing anddefining the invention, this should not inhibit broader or relatedembodiments going beyond the semantic orientation of this applicationbut falling within the spirit of the invention. For example, thoseskilled in the art will understand how to adapt the invention to a widevariety of mixing and refining tasks and will know how to vary theworking surfaces of the rotor and stator within the spirit of theinvention to achieve optimum results.

I claim:

1. in a mixer-refiner having a generally cylindrical stator and acoaxial internal rotor with-confronting surfaces of said rotor and saidstator configured for mixing and refining high-viscosity material, theimprovement comprising:

a. said confronting surfaces of said rotor and said stator each havingdiscrete raised bars arranged and spaced to allow said material to movebetween said raised bars without plugging between said raised bars;

b. a plurality of said raised bars on said rotor and said stator beinginclined relative to the motion between said rotor and stator, some ofsaid inclined bars being oriented to feed said material and some of saidinclined bars being oriented to retard said material;

c. said inclined bars on said stator having a net feed orientationrelative to said material;

d. said inclined bars on said rotor having a net orientation relative tofeed of said material ranging from neutral to a feed orientationsubstantially less than said feed orientation of said inclined bars onsaid stator; and

e. said raised bars on said rotor being configured so that before anylocalized volume between said rotor and said stator completely fillswith said material, said rotor bars engage said material with sufficientforce to move said material through said stator bars.

2. The mixer-refiner of claim 1 wherein said raised bars have slopingleading edges.

3. The mixer-refiner of claim 1 wherein the angle of inclination of saidinclined bars relative to the motion between said rotor and said statoris approximately 4. The mixer-refiner of claim 3 wherein saidinclination of said inclined bars on said stator is approximately 10,and said inclination of said inclined bars on said rotor isapproximately 15.

5. The mixer-refiner of claim 1 wherein the tops of said inclined rotorbars are inclined downward toward the leading edges of said inclinedrotor bars.

6. The mixer-refiner of claim 1 wherein said raised bars on said rotorand said stator each lie in a plane.

7. The mixer-refiner of claim 1 wherein said inclined bars on said rotorare inclined more than said inclinedbars on said stator.

8. The mixer-refiner of claim 1 wherein saidraised bars on said rotorare raised to a greater height than said raised bars on said stator.

' 9. The mixer-refiner of claim 1 wherein said'raised bars on said rotorare shorter than said raised bars on said stator.

10. The mixer-refiner of claim 1 wherein said raised barson said rotorand said stator have sloping side edges.

11. The mixer-refiner of claim 1 wherein said raised bars on said rotorand said stator are arranged in groups that are spaced apart.

12. The mixer-refiner of claim 1 1 wherein said raised bars have slopingleading edges.

13. The mixer-refiner of claim 12 wherein said raised bars on said rotorand said stator each lie in a plane.

14. The mixer-refiner of claim 13 wherein said inclined bars on saidrotor are inclined more than said inclined bars on said stator.

15. The mixer-refiner of claim 14 wherein said raised bars on said rotorare raised to a greater height than said raised bars on said stator.

16. The mixer-refiner of claim 15 wherein the tops of said inclinedrotor bars are inclined downward toward the leading edges of saidinclined rotor bars.

17. The mixer refiner of claim 13 wherein said raised bars on said rotorare shorter than said raised bars on said stator.

18. The mixer-refiner of claim 14 wherein said raised bars on said rotorand said stator have sloping side edges.

19. The mixer-refiner of claim 11 wherein said spaces between said bargroups are generally clear and smooth to allow free movement of saidmaterial in said spaces.

20. The mixer-refiner of claim 11 wherein said raised bars in any one ofsaid bar groups are parallel.

21. The mixer-refiner of claim 11 wherein the inclination of said barsof said rotor changes for rotationally successiveones of said rotor bargroups.

22. The mixer-refiner of claim 11 wherein said groups of said raisedbars are formed respectively on a plurality of removable blocks.

23. Themixer-refiner of claim 22 including clamp bars for holding saidremovable blocks in place.

24. The mixer-refiner ofclaim 23 wherein said blocks are arranged inaxial rows.

25. The mixer-refiner of claim 24 including spacers arranged in saidrows to stagger said rows of blocks from each other. 1

26. The mixer-refiner of claim 25 including means for fixing one of saidclampbars in place at the trailing edge of each of said rows of blocksand means for adjustably tightening another one of said clamp bars onthe leading edge of each of said rows of blocks.

27. The mixer-refiner of claim 23 wherein said rotor and said statorhave longitudinal slots for receiving said clamp bars, and includingscrew means for said clamp bars in said slots.

28. The mixer-refiner of claim 23 wherein said clamp bars providegenerally smooth surfaces between said groups of said raised bars.

29. The mixer-refiner of claim 11 wherein said rotor has an equal numberof said bar groups inclined to retard said material and to feed saidmaterial.

30. The mixer-refiner of claim 11 including groups of said barsgenerally aligned with the direction of relative motion between saidrotor and said stator.

31. The mixer-refiner of claim 11 wherein an input region of said mixerrefiner includes more of said bar groups oriented to feed said materialthan to retard said material.

32. The mixer-refiner of claim 11 wherein an output region of saidmixer-refiner has more of said bar groups oriented to retard saidmaterial than to feed said material.

tightening A

1. In a mixer-refiner having a generally cylindrical stator and acoaxial internal rotor with confronting surfaces of said rotor and saidstator configured for mixing and refining high-viscosity material, theimprovement comprising: a. said confronting surfaces of said rotor andsaid stator each having discrete raised bars arranged and spaced toallow said material to move between said raised bars without pluggingbetween said raised bars; b. a plurality of said raised bars on saidrotor and said stator being inclined relative to the motion between saidrotor and stator, some of said inclined bars being oriented to feed saidmaterial and some of said inclined bars being oriented to retard saidmaterial; c. said inclined bars on said stator having a net feedorientation relative to said material; d. said inclined bars on saidrotor having a net orientation relative to feed of said material rangingfrom neutral to a feed orientation substantially less than said feedorientation of said inclined bars on said stator; and e. said raisedbars on said rotor being configured so that before any localized volumebetween said rotor and said stator completely fills with said material,said rotor bars engage said material with sufficient force to move saidmaterial through said stator bars.
 2. The mixer-refiner of claim 1wherein said raised bars have sloping leading edges.
 3. Themixer-refiner of claim 1 wherein the angle of inclination of saidinclined bars relative to the motion between said rotor and said statoris approximately 10* - 15*.
 4. The mixer-refiner of claim 3 wherein saidinclination of said inclined bars on said stator is approximately 10*,and said inclination of said inclined bars on said rotor isapproximately 15*.
 5. The mixer-refiner of claim 1 wherein the tops ofsaid inclined rotor bars are inclined downward toward the leading edgesof said inclined rotor bars.
 6. The mixer-refiner of claim 1 whereinsaid raised bars on said rotor and said stator each lie in a plane. 7.The mixer-refiner of claim 1 wherein said inclined bars on said rotorare inclined more than said inclined bars on said stator.
 8. Themixer-refiner of claim 1 wherein said raised bars on said rotor areraised to a greater height than said raised bars on said stator.
 9. Themixer-refiner of claim 1 wherein said raised bars on said rotor areshorter than said raised bars on said stator.
 10. The mixer-refiner ofclaim 1 wherein said raised bars on said rotor and said stator havesloping side edges.
 11. The mixer-refiner of claim 1 wherein said raisedbars on said rotor and said stator are arranged in groups that arespaced apart.
 12. The mixer-refiner of claim 11 wherein said raised barshave sloping leading edges.
 13. The mixer-refiner of claim 12 whereinsaiD raised bars on said rotor and said stator each lie in a plane. 14.The mixer-refiner of claim 13 wherein said inclined bars on said rotorare inclined more than said inclined bars on said stator.
 15. Themixer-refiner of claim 14 wherein said raised bars on said rotor areraised to a greater height than said raised bars on said stator.
 16. Themixer-refiner of claim 15 wherein the tops of said inclined rotor barsare inclined downward toward the leading edges of said inclined rotorbars.
 17. The mixer refiner of claim 13 wherein said raised bars on saidrotor are shorter than said raised bars on said stator.
 18. Themixer-refiner of claim 14 wherein said raised bars on said rotor andsaid stator have sloping side edges.
 19. The mixer-refiner of claim 11wherein said spaces between said bar groups are generally clear andsmooth to allow free movement of said material in said spaces.
 20. Themixer-refiner of claim 11 wherein said raised bars in any one of saidbar groups are parallel.
 21. The mixer-refiner of claim 11 wherein theinclination of said bars of said rotor changes for rotationallysuccessive ones of said rotor bar groups.
 22. The mixer-refiner of claim11 wherein said groups of said raised bars are formed respectively on aplurality of removable blocks.
 23. The mixer-refiner of claim 22including clamp bars for holding said removable blocks in place.
 24. Themixer-refiner of claim 23 wherein said blocks are arranged in axialrows.
 25. The mixer-refiner of claim 24 including spacers arranged insaid rows to stagger said rows of blocks from each other.
 26. Themixer-refiner of claim 25 including means for fixing one of said clampbars in place at the trailing edge of each of said rows of blocks andmeans for adjustably tightening another one of said clamp bars on theleading edge of each of said rows of blocks.
 27. The mixer-refiner ofclaim 23 wherein said rotor and said stator have longitudinal slots forreceiving said clamp bars, and including screw means for tightening saidclamp bars in said slots.
 28. The mixer-refiner of claim 23 wherein saidclamp bars provide generally smooth surfaces between said groups of saidraised bars.
 29. The mixer-refiner of claim 11 wherein said rotor has anequal number of said bar groups inclined to retard said material and tofeed said material.
 30. The mixer-refiner of claim 11 including groupsof said bars generally aligned with the direction of relative motionbetween said rotor and said stator.
 31. The mixer-refiner of claim 11wherein an input region of said mixer refiner includes more of said bargroups oriented to feed said material than to retard said material. 32.The mixer-refiner of claim 11 wherein an output region of saidmixer-refiner has more of said bar groups oriented to retard saidmaterial than to feed said material.